Observational Study of the IMF Spiral North and South of the Current Sheet

C. W. Smith and J. W. Bieber

Solar Wind Seven (Proceedings of the 3rd COSPAR Colloquium), ed. by E. Marsch and R. Schwenn, Pergamon Press, pp. 273-276 (1992).


We have analyzed 23 years of spacecraft observations spanning 27 AU. Our analysis reveals both an overwinding of the interplanetary magnetic field (IMF) and a sustained asymmetry between the northern and southern hemispheres of the heliosphere. Nonzero azimuthal field components at the source boundary may account for the observed overwinding. The north-south asymmetry, whereby the IMF spiral north of the current sheet is more tightly wound than the IMF spiral south of the current sheet, persists due to unknown sources. It is also shown that there exist significant, correlated departures from the Parker theory in the azimuthal component of the field.

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